Deoxyribonucleic acid is the most basic molecule needed to form life. DNA needs help from enzymes in order to undergo the complicated and time-consuming replication process. Both helicase and DNA polymerase are involved in DNA replication, but the enzymes perform different functions within the replication process.

DNA Replication

Cells cannot live forever. In fact, most cells in the body only live for a few days or weeks. New cells must continually be formed. DNA must be replicated in order for new cells to form, as most cells form in a process called mitosis. In mitosis, the chromosomes in one cell must separate into two new cells, and each cell needs separate DNA strands found within each chromosome. It takes approximately an hour to replicate a section of a DNA strand, or 50 base pairs each second.

Helicase

The DNA replication process begins with helicase, which signals the DNA strand to unwind. Helicase is made of six proteins that are arranged in a ring. The enzyme uses adenosine triphosphate, an energy source, to help power it down the DNA strand. There are many different types of helicases. For example, human beings have 24 different helicases, while most bacteria have at least 10. Helicases can perform other types of jobs besides unwinding the DNA strand. They may also be used to repair pieces of the DNA strand or transcribe the strand.

DNA Polymerase

Just as helicase is responsible for unwinding the DNA strand, DNA polymerase is responsible for replicating the strand once it unwinds and separates. DNA is made up of a sugar-phosphate ladder and a nucleotide base. As the DNA strand separates, the DNA polymerase matches nucleotide bases that are missing when the strand separates. Most DNA polymerase also has the ability to correct errors in the strand. As there is more than one type of helicase, there is also more than one type of polymerase.

Other Interesting Differences

Helicases have been studied for their links to cancer and the growth of tumors, especially in humans. Helicases are also linked to premature aging and gene stability. While helicases have been studied for their links to human health problems, polymerases have been used to sequence and amplify DNA in a technique called polymerase chain reaction. With the PCR technique, genes can be sequenced, a DNA fingerprint can be gained of an individual for use in identification of a criminal or a body, or an entire group of individuals or animals can be studied and traced to a common ancestor.

About the Author

Lori Garrett-Hatfield has a B.J. in Journalism from the University of Missouri. She has a Ph.D. in Adult Education from the University of Georgia. She has been working in the Education field since 1994, and has taught every grade level in the K-12 system, specializing in English education, and English as a Second Language education.